Graduate School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-Ku, Tokyo, 108-8641, Japan.
School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-Ku, Tokyo, 108-8641, Japan.
Extremophiles. 2024 Aug 27;28(3):41. doi: 10.1007/s00792-024-01357-z.
The peptidoglycan of the hyperthermophile Thermotoga maritima contains an unusual D-lysine in addition to the typical D-alanine and D-glutamate. Previously, we identified the D-lysine and D-glutamate biosynthetic pathways of T. maritima. Additionally, we reported some multifunctional enzymes involved in amino acid metabolism. In the present study, we characterized the enzymatic properties of TM1744 (threonine aldolase) to probe both its potential multifunctionality and D-amino acid metabolizing activities. TM1744 displayed aldolase activity toward both L-allo-threonine and L-threonine, and exhibited higher activity toward L-threo-phenylserine. It did not function as an aldolase toward D-allo-threonine or D-threonine. Furthermore, TM1744 had racemase activity toward two amino acids, although its racemase activity was lower than its aldolase activity. TM1744 did not have other amino acid metabolizing activities. Therefore, TM1744 is a low-specificity L-threonine aldolase with limited racemase activity.
嗜热栖热菌的肽聚糖除了含有典型的 D-丙氨酸和 D-谷氨酸外，还含有一种不寻常的 D-赖氨酸。以前，我们鉴定了嗜热栖热菌的 D-赖氨酸和 D-谷氨酸生物合成途径。此外，我们还报道了一些参与氨基酸代谢的多功能酶。在本研究中，我们对 TM1744（苏氨酸醛缩酶）的酶学性质进行了表征，以探究其潜在的多功能性和 D-氨基酸代谢活性。TM1744 对 L-allo-苏氨酸和 L-苏氨酸均表现出醛缩酶活性，对 L-threo-苯丙氨酸的活性更高。它对 D-allo-苏氨酸或 D-苏氨酸没有醛缩酶活性。此外，TM1744 对两种氨基酸具有消旋酶活性，尽管其消旋酶活性低于醛缩酶活性。TM1744 没有其他氨基酸代谢活性。因此，TM1744 是一种低特异性的 L-苏氨酸醛缩酶，具有有限的消旋酶活性。
